For 800,000 years before the twentieth century, carbon dioxide levels in Earth’s atmosphere never exceeded 300 parts per million. In March 2015, the monthly average went above 400 ppm for the first time.

In addition to its primary mission of observing space weather, the Deep Space Climate Observatory (DSCOVR) satellite is carrying two instruments that are important to climate science: the NISTAR radiometer and the EPIC camera.

Since 2004, researchers in NOAA’s Global Monitoring Division have released the Annual Greenhouse Gas Index: a single value that compares the total warming effect of each year's concentrations of heat-trapping gases to 1990 levels.

CarbonTracker is a tool for modelling sources and sinks of carbon dioxide. Users can download the code, carbon dioxide data, and the tool's carbon flux estimates to conduct their own analyses or to help improve the system.

NOAA released the 2012 installment of the annual Arctic Report Card on December 5, 2012, as part of the American Geophysical Union's fall meeting. This image collection is a gallery of highlights based on the report's major themes. It was developed by the NOAA Climate.gov team in cooperation with Arctic Report Card authors and other Arctic experts.

Although they are related, meteorology and climatology have important differences, particularly in how scientists develop and use weather and climate models. What makes climatologists think they can project climate scenarios decades into the future when meteorologists cannot accurately predict weather more than two weeks in advance? This presentation by Wayne Higgins of NOAA's Climate Prediction Center clarifies the relationships and differences between weather and climate, as well as the differences between natural climate variability and human-induced climate change.

James Roger Fleming presents a historical perspective on how our understanding of Earth's climate system developed through innovations and discoveries by pioneering scientists in the 1800s and 1900s who asked and answered fundamental questions about the causes and effects of global climate change.